1. Field of the Invention
The present invention relates to a counter-stream-mode oscillating-flow heat transport apparatus which creates oscillations of counterflow fluid mediums in adjacent flow paths and microchannels to thereby exchange heat between the adjacent flow paths and transport heat from a hot region to a cold region, the apparatus being effectively applicable to a thermally quasi-superconductive plate, a thermal switch, a thermal diode, and so forth.
2. Description of the Related Art
As can be found in the URL, “http://www.iis.u-tokyo.ac.jp/topics/1nishio.html,” dated May 31, 2002, the counter-stream-mode oscillating-flow heat transport apparatus is based on a principle that employs no phase change. The principle of transferring heat in the counter-stream-mode oscillating-flow heat transport apparatus relies on the so-called “enhanced heat diffusion effect” which is produced by oscillating flows, as described in the aforementioned URL.
To describe the effect in more detail, suppose that a liquid-filled conduit has a temperature distribution as shown in FIG. 22. For simplicity, consider a rectangular wave oscillation in which an oscillation of the liquid stays at point H for half a cycle and is then immediately transferred to point L and stays there for the other half cycle, and is then immediately transferred back to point H.
Take a liquid portion, referred to as an element, at point C in absence of oscillation. When this element is oscillated to move to point H, the element accepts heat from the wall of the conduit because the temperature at point H on the wall is higher than that of the element. When the element is further oscillated to move to point L, the element releases heat to the wall since the temperature at point L on the wall is lower than that of the element.
In other words, one oscillation causes heat to be transferred from point H to point L, like a frog jumps from one place to another. Such a jump would never occur in absence of an oscillation. Furthermore, the heat transfer or “jump” occurs simultaneously with the oscillation. Thus, the higher the frequency of the oscillation, the larger the number of jumps per unit time becomes, while the larger the amplitude, the greater the distance a jump becomes. That is, the accompanying displacement of heat due to the jump increases with an increase in amplitude and cyclical action. However, an increase in amplitude and cyclical action for a greater amount of heat displacement would cause an increase in the flow path resistance the pump load for inducing oscillation in a liquid.
To effectively release heat from a heat-generating element having high heat fluxes, it is critical to provide an improved coefficient of heat transfer with a heating medium (such as water or air). The improvement in the heat transfer coefficient can be achieved by allowing the heating medium to flow through a microchannel (micro-machined) flow path.
Accordingly, the higher the frequency of the oscillation, the larger the number of jumps per unit time becomes, and the larger the amplitude, the greater the distance of a jump. Thus, the accompanying displacement of heat provided by the jump increases with an increase in amplitude and cycle (e.g., see Japanese Patent Laid-Open Publication No. 2002-364991).
On the other hand, the counter-stream-mode oscillating-flow heat transport apparatus induces oscillations in a fluid through a serpentine flow path to thereby create oscillations of counterflow fluids in adjacent flow paths, and thus the apparatus has to be provided with serpentine flow paths. In this context, the inventors devised the following two methods for manufacturing the serpentine flow paths.
That is, as shown in FIG. 47, according to a first manufacturing method, there is provided a multi-hole tube 41 having a plurality of holes 46 formed to penetrate from one end to the other end along the length of the tube. Plates 51 are also provided which each have recesses 50 for allowing adjacent holes 46 to communicate with each other and which are coupled to both ends of the multi-hole tube 41.
On the other hand, as shown in FIG. 48, according to the second manufacturing method, there is also provided a multi-hole tube 41 having a plurality of holes 46 formed to penetrate from one end to the other end along the length thereof. The multi-hole tube 41 is constructed such that bounding walls for defining a boundary of adjacent holes 46 are alternately cut or formed in a similar manner at both the longitudinal ends thereof so as to allow adjacent holes 46 to communicate with each other inside the multi-hole tube 41 at the longitudinal ends. The longitudinal ends of the multi-hole tube 41 are each blocked with a strip plate 52.
However, the first manufacturing method requires the plates 51 having the recesses 50 provided at a plurality of portions therein to be separately manufactured. The plates 51 having the recesses 50 provided at a plurality of portions therein are complicated in shape. This leads to an increase in manufacturing costs of the counter-stream-mode oscillating-flow heat transport apparatus.
The second manufacturing method requires an additional process of alternately cutting the bounding walls at the longitudinal ends thereof, or the like, after the multi-hole tube 41 has been fabricated. This also results in an increase in manufacturing costs of the counter-stream-mode oscillating-flow heat transport apparatus.
Like the condenser tube employed in a vehicular air conditioner, the multi-hole tube has a plurality of holes 46 formed to penetrate from one end to the other end along its length and can be fabricated by an extrusion process or by a drawing process. Although the microchannel has a high heat transfer coefficient, its reduced flow path area leads to a high pressure loss. This raises a problem that a high power pump is required for the heating medium to circulate through the flow path. Furthermore, the microchannel is typically fabricated by cutting or etching; however, these methods lead to an increase in manufacturing costs for the microchannel.